Effect Of Dopeing Rare Earth On Ferrites Microwave Absorbing Performance

axFe2-xO4 spinel ferrite and SrLao.3Coo.3Tio.3Fe11.4O19 hexaferrite was prepared by sol-gel method, and their crystal structure and microwave absorption properties were analyzed by XRD and microwave vector network analyzer. The results indicate that when they respectively sintered at 1000℃,800℃, the absorbing performance of Ni0.4Co0.24Zn0.36LaxFe2-xO4 spinel ferrite and SrLa0.3Co0.3Ti0.3Fe11.4O19 hexaferrite is best.In Ni0.4Co0.24Zn0.36LaxFe2-xO4(x=0,0.03,0.05,0.07,0.1)five different samples doped lanthanum, we find that when the mol ratio of rare earth is 0.07, the highest absorption value reaches38.55dB, and the absorption value reaches more than 15dB almost in all frequency band which is beneficial to high frequency absorbing material. In Sr1-xLaxCo0.3Ti0.3Fe11.4O19(x=0,0.1,0.2,0.3,0.4) five different samples doped lanthanum, we also find that when the mol ratio of rare earth is 0.3, the highest absorption value reaches 42.37dB, effective band width of more than 10dB reaches 2.90GHz and more than 20dB reaches 2.33GHz.Imaginary part of dielectric constant (ε") and permeability (μ") of the samples are measured. The results of experiments indicate that the imaginary part of dielectric constant has not notable rule as doping different amount of rare earth. But the frequency corresponding to the peak of imaginary part of permeability is close to the frequency corresponding to the peak of absorption, and their changing rule is similar.Therefore, Ni0.4Co0.24Zn0.36LaxFe2-xO4 spinel ferrite and SrLa0.3Co0.3Tio.3Fe11.4O19 hexaferrite of doping lanthanum influce their microwave absorption mainly through the impact of magnetic loss.